Recently, as a developing step for photographic light-sensitive materials (hereinafter, is referred to as photographic materials), high-temperature rapid processing has been widely used and in processing various kinds of photographic materials by automatic processors, thus the processing time has been greatly shortened. For attaining rapid processing, it is necessary to have a developer for attaining a sufficient sensitivity in a short time, a photographic material which is excellent in the development proceeding property and gives a sufficient blackened density in a short time, and that the photographic material is capable of being dried in a short time after washing.
As a method generally used for improving the drying property of photographic materials, there is a method in which the water content in a photographic material is reduced before drying thereof by previously adding a sufficient amount of a hardening agent (gelatin crosslinking agent) to the photographic material in the coating step for preparing the photographic material to reduce the swelling amount of the silver halide emulsion layer(s) and the hydrophilic colloid layer(s) thereof in the development-fixing-washing steps. In the method, when a large amount of the hardening agent is used, the drying time can be shortened, but in this case, since the swelling amount of the layers is reduced too much, such that the development is delayed, the sensitivity is lowered, the contrast is lowered, and the covering power in lowered. Also, even when the development proceeding property is improved, the ability to shorten the processing time may be hindered by the delay of the fixing speed caused by the highly hardened layers, which causes the problems of residual silver, residual hypo, and residual colors of sensitizing dyes.
On the other hand, a method for increasing the developing activity of a processing solution is known and it is possible to increase the activity by increasing the amounts of the developing agent and the auxiliary developing agent in a developer, increasing the pH of a developer, and/or increasing the processing temperature. However, these methods all have disadvantages that the preservability of a processing solution is spoiled and even if the sensitivity may be increased, the contrast is lowered and the processed photographic materials are liable to be fogged.
For overcoming the disadvantages described above, a technique of using tabular grain silver halide emulsions is described in U.S. Pat. Nos. 4,439,520, 4,425,425, etc. Also, JP-A-63-305343 and JP-A-1-77047 (the term "JP-A" as used herein means an "unexamined published Japanese Patent application") which disclose a technique of improving the development proceeding property and the sensitivity/fog ratio by controlling the development initiating points of a silver halide grain having (111) planes at or near the tops and/or the edges of the grains. Furthermore, JP-A-58-111933 discloses a radiographic photographic element having a high covering power and without need of supplementing a hardening agent at processing by lowering swelling ratio of hydrophilic colloid layer(s) containing tabular silver halide grains to 200% or less.
These known techniques are excellent techniques in improving the development proceeding property of photographic materials and they have a high utilization value. However, when the processing time for the steps of development, fixing, and washing is shortened, the photographic sensitivity is lowered and the fixing property is deteriorated, resulting in an increase of residual silver and residual hypo. Also, residual colors occur in processing a photographic material that has been subjected to spectral sensitization with sensitizing dyes. Thus, there is a limit in the improvement of photographic properties by the conventional methods of improving silver halide grains because the conventional methods are unable to produce high quality photographic layers. That is, the thickness of the hydrophilic colloid layer(s) determines the fixing property and the production of residual colors and hinders the ability to increase the processing speed.
In regard to the point, JP-A-64-73333, JP-A-64-86133, JP-A-1-105244, JP-A-1-158435, JP-A-1-158436, etc., disclose a means for attaining super rapid processing of the total processing time of from 20 seconds to less than 60 seconds by adjusting the amount of gelatin of the side having hydrophilic colloid layers including silver halide emulsion layer(s) in the range of from 2.00 to 3.50 g/m.sup.2 and combining with other technical elements. Also, JP-A-2-68537 discloses a means of attaining super rapid processing by adjusting the weight ratio (silver/gelatin) of silver of light-sensitive silver halides in silver halide emulsions formed to gelatin in the layers to at least 1.5. Furthermore, JP-A-63-221341 discloses a means of attaining super rapid processing of the total processing time of from 20 seconds to 60 seconds by employing silver halide emulsion(s) containing silver halide grains mainly composed of tabular silver halide grains having an aspect ratio of at least 5, adjusting the gelatin amount of the emulsion layers to the range of from 2.00 to 3.20 g/m.sup.2 and adjusting the melting time to the range of from 8 minutes to 45 minutes.
Also, JP-A-4-128832 and JP-A-4-324854 disclose a means of attaining super rapid processing by adjusting the coated amount of gelatin, the silver/gelatin ratio of the silver halide emulsion layer(s), and the content of silver iodide in the silver halide grains to the optimum values.
As the result of investigating these prior techniques, the inventors have confirmed that when the amount of a binder such as gelatin, etc., is simply reduced, and when the photographic films are transported by rollers in an automatic processor, the films are rubbed with the rollers forming scratches and causing peeling of the layers. Also, it has been confirmed that when only the swelling ratio of the photographic layers is lowered, the hardness of the layers increases, as described above, causing an increase in residual colors, residual silver, residual hypo, etc., whereby the photographic materials are rendered unsuitable for super rapid processing.
Furthermore, as the result of further investigating the prior techniques described above, the inventors have confirmed that when the amount of gelatin is reduced and/or the silver/gelatin ratio is increased and the coated silver amount is maintained at a constant ratio, abrasion blackening and roller marks increase on the film to a practically unallowable level, whereby the photographic materials cannot be processed by super rapid processing.
The term "abrasion blackening" means that when photographic films are handled and when the films are abraded with each other or the film is abraded with other material, abrasion-shaped blackening is formed after development processing. Also, the term "roller marks" means that when a photographic material is processed by an automatic processor, a pressure is applied to the light-sensitive material by the fine unevenness on the surfaces of the transport rollers, which results in forming a black spot-like uneven density.
When the total processing time is shortened to 60 seconds or less, in particular 40 seconds or less, as the result of properly distributing the times for the development, fixing, and washing steps, when the environmental condition of an automatic processor is a high humidity, it sometimes happens that the drying property of the photographic material is hindered if the swelling amount of the hydrophilic colloid layers of the photographic material is not 10 .mu.m or lower.
As the result of investigating a means of preventing the occurrence of the abrasion and the roller marks when the swelling amount of the hydrophilic colloid layers is not more than 10 .mu.m, the inventors have found that when the amount of silver chloride contained in the silver halide emulsion is increased, there is a tendency of solving the foregoing problem.
On the other hand, in the example of using a tabular grain silver halide emulsion described in JP-A-58-111933, the coated amount of gelatin in the sample is 2.87 g/m.sup.2 and hardening is sufficient, whereby there is no problem on drying, but it has been found that when the total processing time is shortened to 40 seconds or less, there are problems with the fixing property and residual colors.
Also, JP-A-2-68537 discloses an example wherein the coated amount of gelatin per one surface side of the support is 2.5 g/m.sup.2 and silver chlorobromide and silver bromide each containing no silver iodide are used. However, the sensitivity of silver bromide and silver chlorobromide in the example is greatly lower than that of the tabular silver chlorobromide gains having (100) planes in the present invention.
Silver halide emulsions containing tabular silver halide grains having (100) planes as the major planes are described, e.g., in JP-A-51-88017, JP-B-64-8323 (the term "JP-B" as used herein means an "examined published Japanese Patent application"), and European Patent 0534,395A1.
However, in the tabular grain silver halide emulsion containing silver chloride, the mixing ratio of twin grains is high and the grain size distribution is broad as shown in the silver halide grain photographs of the example of European Patent 0534,395A1. For example, in the photograph shown in FIG. 1 of the European patent specification described above, it is considered that since the number of silver halide grains is large, the reliability of the existence probability thereof is high but according to FIG. 1, the ratio a.sub.4 =(the total projected area of the twin grains/the total projected area of the (100) plane tabular silver halide grains having an aspect ratio of at least 2) is about 0.11. Also, the coefficient of variation of the grain size distribution of the tabular silver halide grains having a thickness of 0.35 .mu.m or lower is broad. In particular, the diameter distribution of the grains having a large projected area is important for the photographic properties and the diameter distribution is broad. For example, in the case of collecting the tabular silver halide grains in the order of the larger projected area up to 70% of the total projected area, the coefficient of variation (standard deviation/average diameter) of the diameter distribution is over 0.12. Also, the projected area ratio of the tabular grains having the edge ratio (the edge length of the long edge/the edge length of the short edge) of not higher than 1.4 is low. For example, in the photograph shown by FIG. 1 of the foregoing patent specification, the edge ratio is about 0.4. Such values reduce the sensitivity and the gradation of the photographs.